Meteorological droughts are projected to worsen in Central America’s dry corridor throughout the 21st century

Abstract

Understanding past and projected drought patterns across Central America’s ‘Dry Corridor’ (CADC) is crucial for adaptation planning and impact mitigation, especially in small-scale agricultural communities. We analyzed historical and predicted drought patterns in the CADC by calculating Standardized Precipitation Index (SPI) values from local rain gauge records, reanalysis data and a 20-member ensemble of bias-corrected, downscaled CMIP-5 GCMs at both seasonal (3 month) and annual (12 month) scales. Trends in drought frequency, duration, intensity were assessed for three, 30 year future periods compared to historical values. Our results suggest a decrease in mean annual rainfall of 8%–14% in the CADC under moderate to high emissions scenarios, respectively, by end-of-century (2071–2100) relative to a historical baseline (1950–2005). However, projected changes to drought characteristics under these scenarios are more pronounced, with seasonal-scale droughts projected to lengthen by 12%–30%, intensify by 17%–42% and increase in frequency by 21%–24% by end-of-century. Annual-scale, longer-term droughts are projected to lengthen by 68% under moderate emissions, potentially triple in length under high emissions and to intensify by 27%–74%. These results were similar yet slightly more pronounced for some drought metrics when just considering rainy/cropping season months (May–Oct). End-of-century changes to rainfall reliability and drought occurrence such as these would severely impact millions of vulnerable inhabitants in the CADC and should be considered in adaptation policymaking efforts.

Natural variability vs forced signal in the 2015–2019 Central American drought

“…The extent of the precipitation anomaly observed between 2015 and 2019 revealed a key role for rainfall in this multi-year drought, leading us to focus on precipitation as the dominant variable to characterize this event. Indeed, recent studies highlight the projected precipitation reduction over Central America as the key factor in the increase of drought risk in the coming decades (Giorgi 2006;Rauscher et al 2008;Fuentes-Franco et al 2015;Almazroui et al 2021;Depsky and Pons 2020). However, it is also important to mention that regional ongoing warming trends (Aguilar et al 2005;Gourdji et al 2015) play an important role in driving enhanced evapotranspiration and thus further exacerbating future droughts (Hidalgo et al 2021(Hidalgo et al , 2019Alfaro-Cordoba et al 2020).…”

“…Summer precipitation over Central America shows a marked decadal variability resulting from modes of large scale variability like El Niño-Southern Oscillation, the Atlantic Multidecadal Oscillation, and the North Atlantic Oscillation (Giannini et al 2000(Giannini et al , 2001Wang 2007;Hastenrath and Polzin 2013;Muñoz-Jimènez et al 2019;Anderson et al 2019;Hidalgo et al 2019). Climate projections from global and regional models consistently suggest a reduction of summertime precipitation between May and September in Central America by the end of this century, along with higher summer temperatures (Giorgi 2006;Rauscher et al 2008;Fuentes-Franco et al 2015;Hidalgo et al 2013;Almazroui et al 2021;Depsky and Pons 2020). This raises the question of whether Anthropogenic Climate Change (ACC) has contributed to the 2015-2019 meteorological drought and to the 40-year negative trend, increasing their likelihood.…”

WFP’s Contributions to Improving the Prospects for Peace in the Central American Dry Corridor: Spotlight on Climate Change

“…They are also projected to intensify by 17-42 per cent across all months and by 21-51 per cent during the rainy season. 68 Long-term droughts are also projected to become more severe by 2100, intensifying by 27-73 per cent, depending on the scenario, across all months, and by 27-75 per cent in the rainy season. 69 Periods of 'seasonal hunger' in the Dry Corridor are likely to be extended, especially in El Niño years.…”

Diagnostics of observed dry trends in Caribbean precipitation

“…With a remarkable consistency, different model simulations have predicted that precipitation in the Caribbean will decrease in the coming decades as a result of the effects of global warming (e.g. Almazroui et al ., 2021; Campbell et al ., 2011; Chen et al ., 2018; Depsky and Pons, 2020; Hall et al ., 2013; Imbach et al ., 2018; IPCC, 2021; Karmalkar et al ., 2013; Kumar et al ., 2013; Maloney et al ., 2014; Neelin et al ., 2006; Rauscher et al ., 2011; Taylor et al, 2011; Taylor et al ., 2018; Stocker et al ., 2013). Future dry conditions in the Caribbean are important not only from a scientific perspective, as they might be the most robust precipitation signals associated with the effects of global warming, but they are more important because their potential impacts might increase poverty, violence and forced migration among the most vulnerable populations (e.g.…”